The third person camera regards powder snow as transparent and moves through it just like glass, although you cannot look through it.

To reproduce

1. Build a wall of powder snow
2. Stand in front of it
3. Enable third-person camera (F5)
   → Notice that the camera is placed in front of the wall and you cannot see yourself

Video

Minecraft 20w46a - Singleplayer 2020-11-11 22-11-57.mp4